clang-tidy - misc-new-delete-overloads

The check flags overloaded operator new() and operator delete()
functions that do not have a corresponding free store function defined within
the same scope.
For instance, the check will flag a class implementation of a non-placement
operator new() when the class does not also define a non-placement operator
delete() function as well.

The check does not flag implicitly-defined operators, deleted or private
operators, or placement operators.